This invention relates generally to semiconductor manufacturing and more particularly to a method and system for reducing by-product deposition in wafer processing equipment.
During the manufacture of semiconductor components, such as integrated circuits, memory chips, and the like, the failure of valves and pumps used in connection with wafer processing equipment is problematic. The failure is often caused by the deposition of by-products, such as by deposition of ammonium chloride (NH4Cl). In certain chemical vapor deposition (xe2x80x9cCVDxe2x80x9d) processes such as chloride-based ammonium reduction CVD processes, ammonia chloride (NH4Cl) is formed by reacting, for example, hydrogen chloride (HCL) with ammonia (NH3). The resulting ammonia chloride may sublimate to a solid and stick to the inside of a wafer processing chamber wall or on the inside of associated valves and pumps. The build up over time of solidified ammonium chloride inside the valves and pumps may cause the valves to leak and the pumps to degrade, and the solidified ammonium chloride may also be transmitted into the process chambers, contaminating the manufacturing processes and reducing their yield.
One attempt at solving such a problem involves placing heaters around the wafer processing chamber or associated pump or conduits to maintain the produced ammonium chloride in a gaseous form to prevent sublimation to a solid form. However, in single wafer processing reactors for chemical vapor deposition of silicon nitride (SiCl2H2 and NH3 reaction) and titanium nitride (TiCl4 and NH3 reaction), process gases from a shower head flow into and through a chamber with high velocity and low temperatures. This flow removes a large amount of heat from inner walls of the reaction system. Because of the removal of heat from the inner walls, heating the outer walls may not be sufficient to prevent sublimation of ammonium chloride to a solid form.
Accordingly, a need has arisen for an improved method and system for reducing ammonium chloride deposition in wafer processing equipment. The present invention provides a method and system for reducing ammonium chloride deposition in single wafer processing equipment that addresses shortcomings of prior systems and methods.
According to one embodiment of the invention, a method of reducing by-product deposition inside wafer processing equipment includes providing a chamber having a peripheral inner wall and placing a semiconductor wafer within the chamber. The method also includes placing a ring within the chamber proximate the peripheral inner wall and introducing a plurality of reactant gases into the chamber and reacting the gases. The method also includes introducing a heated gas into the chamber through the ring proximate the peripheral inner wall to increase the temperature of the peripheral inner wall.
According to another embodiment the invention, a method of reducing by-product deposition inside wafer processing equipment includes providing a chamber and placing a semiconductor wafer within the chamber. The method also includes connecting the chamber to a pump through a conduit and placing a heating element within the interior of the conduit to increase a temperature within the conduit. The method also includes introducing a plurality of reactant gases into the chamber and reacting the gases.
Embodiments of the invention provide numerous technical advantages. For example, in one embodiment of the invention, introduction of a heated gas through a ring along the periphery of the inner wall of a chamber inhibits solidification of by-products in wafer processing, such as ammonium chloride. Such inhibiting reduces degeneration of associated valves and pumps. In addition, the amount of solidified by-product contaminating the manufacturing process is reduced, which increases the yield of the manufacturing process.
Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.